In the design of certain types of battery cells, particularly but not exclusively Lithium-ion (“Li-ion”) cells, two design approaches are commonly used. One approach is a so-called “jelly roll” design, which involves rolling two thin metal sheets that form the anode and cathode electrodes, respectively, about a spindle or mandrel, to form multiple layers of both anode and cathode. The other approach is a so-called stacked design, in which the anode and cathode are each formed of physically distinct thin metal sheets, which are stacked on top of one another to form multiple layers of both anode and cathode. The individual electrode layers, or “substrates,” are normally separated by a coating on each layer and/or by other insulative material placed between the electrode layers.
In a stacked design, the individual electrode substrates are typically welded to a thin metal tab that, when the battery is fully assembled, protrudes from the battery package to form an external connection terminal of the battery. One such tab forms the anode terminal of the battery cell and another such tab forms the cathode terminal of the battery cell. Ultrasonic welding is commonly used to bond the substrates to their respective tabs.